The U.S. Supreme Court heard arguments Monday in a case that seeks to redefine a federal law aimed at streamlining the nation's voter registration process.

Congress enacted the law 20 years ago after it found that 40 percent of eligible voters were not registered to vote. Under the 1993 National Voter Registration Act, people can register by mail to vote in federal elections using a standard federal form. The form, among other things, asks prospective voters whether they are U.S. citizens and requires them to sign to the statement, under penalty of perjury.

At the time the federal law was passed, Arizona and half the other states had similar registration forms. But Arizona voters subsequently approved a referendum that requires further proof of citizenship — a birth certificate, naturalization form or passport, for instance. A federal appeals court struck down the Arizona law, saying that it conflicts with and is trumped by federal law. Arizona appealed to the Supreme Court, where the justices heard arguments Monday.

Opponents of the Arizona law argued that it is unnecessarily burdensome and improperly prevents U.S. citizens from voting. SevaPriya Barrier, a native of Arkansas, was one of those citizens affected by the Arizona law and was at the high court on Monday. She moved to Arizona shortly before the 2010 federal elections and tried to register to vote with the federal form. "At the time that I filled it out and submitted it, I did not have an Arizona driver's license yet. My registration was rejected for failure to provide that proof of citizenship," she said.

Barrier adds that she received the rejection notification after the deadline to register had passed.

"So I was denied that fundamental right to vote," she said.

But Arizona Attorney General Thomas Horne counters that the federal system does not provide a sufficient guarantee of citizenship, "because it's an honor system." The federal regime essentially says "if you sign and say you're a citizen, we have to believe you," he says.

Arizona's Arguments

Inside the courtroom, the justices gave both sides a very hard time, starting with Horne.

Justice Sonia Sotomayor interrupted Horne to ask the first question, going straight to the purported justification for the state proof-of-citizenship law: "Why would you think that Congress ... didn't consider the issue of fraud" and strike "the balance it wanted" when it enacted the federal law?

Justice Ruth Bader Ginsburg followed up with this observation: "Congress did specify how citizenship was to be handled" — Congress decided to use "a signed attestation subject to the penalty of perjury. So it's not as though the federal form" didn't deal with citizenship. It did, and Arizona's law is adding "something else."

Justice Elena Kagan pursued the point: Why have a federal form if Arizona could just say that, in addition, "you have to give 10 more items of information? Then the federal form just becomes another hoop to jump through."

Noting that the federal Election Assistance Commission is charged with approving any state-specific instructions to the federal form, Justice Antonin Scalia asked whether Arizona had asked to add on the proof-of-citizenship requirement to the federal form.

The state had asked for the change, but had been denied, replied Horne.

Scalia asked: Why didn't you go to court to challenge that?

"I don't know," replied Horne. That decision was made by "my predecessor."

Justice Anthony Kennedy, who could well cast the deciding vote in the case, wondered whether the state could also ask for proof of address or proof of date of birth on the form.

Horne replied that the state could add those requirements if the federal commission found them to be consistent with the federal law.

Kennedy went on to opine that the federal form "is not worth very much." And Horne pointed out that some states — for example, Louisiana — had been allowed to require a Social Security number or utility bill to prove residency.

"Yes, that's the kind of thing you should have had and that your predecessor should have asked for to be included in the federal form," Scalia said in response.

But under federal law, Horne argued, the states still have the ultimate responsibility to determine voter eligibility, and so the state should be allowed to require proof of citizenship beyond what is required in the federal form.

Kennedy, however, noted that those challenging the Arizona law would argue that the federal form is "presumptive evidence" of registration, unless the state has actual evidence to the contrary. "Otherwise, the whole utility of a single form is ... gone."

The Challengers' Arguments

Next up to the lectern was Patricia Millett, representing those challenging Arizona's proof-of-citizenship requirement. Arizona, she said, "simply disagrees with the balance that Congress drew." Under Arizona's proof-of-citizenship requirement, 31,000 people were rejected from voting. Of those, 11,000 subsequently registered, she said, but they had to "do the double gantlet that Congress was trying to eliminate."

Noting that the federal law requires states to "accept and use" the federal form, Justice Samuel Alito asked whether that means the state can make no further inquiry of the person.

In essence, Millett said yes, but she added that the state may check the voter's information against other databases in its files — for example, to make sure that a felon does not vote and to ascertain that the registrant lives at the address he gave.

Chief Justice John Roberts seemed dubious about the whole system and wondered how a state system could work separately for state and federal elections. He asked: Would there be two separate voter registration rolls?

In fact, every state has, in the interest of economy, hitched its wagon to the federal registration system. No state has separate systems for state and federal elections.

But some justices still seemed skeptical.

"This seems to me like a crazy system," Alito observed.

"It seems to me," said Kennedy, that when the lower court struck down Arizona's law it ignored "the proposition that the state has a very strong and vital interest in the integrity of its elections, even when those ... are elections of federal officials."

A decision in the case is expected by summer.

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Transcript

MELISSA BLOCK, HOST:

This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.

ROBERT SIEGEL, HOST:

And I'm Robert Siegel.

Twenty years ago, Congress enacted a law aimed at streamlining voter registration. The law was motivated by a finding that 40 percent of Americans who were eligible to vote were not registered. Well, today, the meaning of that law was the subject of arguments before the Supreme Court.

NPR legal affairs correspondent Nina Totenberg was at the court.

NINA TOTENBERG, BYLINE: Under the 1993 National Voter Registration Act, voters can register by mail to vote in federal elections. The form, among other things, asks prospective voters whether they are U.S. citizens and requires them to sign under penalty of perjury.

At the time the federal law was enacted, Arizona and about half the other states had similar registration forms. But Arizona voters later passed a referendum that requires further proof of citizenship: a birth certificate, naturalization form, or passport, for instance. A federal appeals court struck down the Arizona law, saying that it conflicts with and is trumped by the federal law for federal elections.

Today in Washington, on the steps of the Supreme Court, SevaPriya Barrier, a native of Arkansas, described what happened to her when she moved to Arizona and tried to register with the federal form.

SEVAPRIYA BARRIER: At the time that I filled it out and submitted it, I did not have an Arizona driver's license yet. My registration was rejected for failure to provide that proof of citizenship.

TOTENBERG: She says she received the rejection after the deadline to register had passed.

BARRIER: So I was denied that fundamental right to vote.

TOTENBERG: But Arizona Attorney General Thomas Horne counters that the federal system does not provide enough of a guarantee that the registering voter is really a citizen.

THOMAS HORNE: It's an honor system. It says, if you sign and say you're a citizen, we have to believe you.

TOTENBERG: Inside the Supreme Court chamber today, the justices gave both sides a very hard time, starting with Horne.

Justice Ginsburg: Congress did specify how citizenship was to be handled - a signed attestation subject to a penalty of perjury. So it's not as though the federal form didn't deal with citizenship. It did, then Arizona adds something else.

Justice Kagan: Why have a federal form if Arizona could just say and in addition, you have to give 10 more items of information? Then the federal form just becomes another hoop to jump through.

Justice Sotomayor: Why would you think that Congress didn't consider the issue of fraud and struck the balance it wanted?

Justice Scalia posed a different question. Noting that a federal elections commission is charged with approving state additions to the federal form, he asked whether Arizona had asked to add a proof of citizenship to that form.

Attorney General Horne replied that the state had asked for the change but been denied.

Justice Scalia: Why didn't you go to court to challenge that?

I don't know, replied Horne. That was under my predecessor.

Justice Kennedy: Could you also ask for proof of address and date of birth on the form?

Answer: We could have if the commission found it to be consistent with the act.

Justice Kennedy went on to opine that the federal form, quote, "is not worth very much." A few minutes later, however, Kennedy said that the federal form is presumptive evidence of registration. Otherwise, the whole utility of a single form is gone.

Next up to the lectern was Patty Millett, representing those who are challenging the Arizona proof of citizenship law. Arizona, she said, simply disagrees with the balance that Congress drew. Under Arizona's proof of citizenship law, 31,000 people were rejected from voting. Eleven thousand of them subsequently registered, she said, but they had to do the double gantlet that Congress was trying to eliminate.

Justice Alito, noting that the federal law requires states to accept and use the federal form, asked whether that means the state can make no further inquiry of the person.

Millett said, in essence, yes, but that the state may check the voter's information against other databases, for instance, to make sure that the registrant is not a convicted felon and does in fact live at the address cited.

Chief Justice Roberts seemed dubious about the whole system and wondered how a state system could work separately for state and federal elections. Would there be two separate voter registration rolls, he asked.

In fact, every state has, in the interest of economy, hitched its wagon to the federal registration system. No state has two separate systems for state and federal elections. But some justices still seemed skeptical.

Justice Alito: This seems to me like a crazy system.

Justice Kennedy: It seems to me that the federal law ignores the proposition that the state has a very strong and vital interest in the integrity of its elections even when those elections are of federal officials.